WebSockets Next: add support for Kotlin suspend functions

Kotlin `suspend` functions are treated like Java methods that return `Uni`.
That is, they are considered non-blocking. The implementation uses CDI
method invokers (to avoid custom bytecode generation), which actually
convert the `suspend` function result into a `Uni` under the hood.

With this commit, only single-shot `suspend` functions are supported;
`suspend` functions returning `Flow` are not supported yet.

bom/application/pom.xml

@@ -2166,6 +2166,11 @@
                 <artifactId>quarkus-websockets-next-deployment</artifactId>
                 <version>${project.version}</version>
             </dependency>
+            <dependency>
+                <groupId>io.quarkus</groupId>
+                <artifactId>quarkus-websockets-next-kotlin</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                 <groupId>io.quarkus</groupId>
                 <artifactId>quarkus-undertow-spi</artifactId>

docs/src/main/asciidoc/kotlin.adoc

@@ -504,6 +504,9 @@ The following extensions provide support for Kotlin Coroutines by allowing the u
 |`quarkus-vertx`
 |Support is provided for `@ConsumeEvent` methods
 
+|`quarkus-websockets-next`
+|Support is provided for server-side and client-side endpoint methods
+
 |===
 
 === Kotlin coroutines and Mutiny

extensions/websockets-next/deployment/pom.xml

@@ -65,10 +65,56 @@
             <artifactId>smallrye-certificate-generator-junit5</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.smallrye.reactive</groupId>
+            <artifactId>mutiny-kotlin</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <version>${kotlin.version}</version>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirs>
+                                <sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
+                                <sourceDir>${project.basedir}/src/main/java</sourceDir>
+                            </sourceDirs>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>test-compile</id>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirs>
+                                <sourceDir>${project.basedir}/src/test/kotlin</sourceDir>
+                                <sourceDir>${project.basedir}/src/test/java</sourceDir>
+                            </sourceDirs>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
@@ -80,6 +126,32 @@
                         </path>
                     </annotationProcessorPaths>
                 </configuration>
+                <executions>
+                    <!-- Replacing default-compile as it is treated specially by Maven -->
+                    <execution>
+                        <id>default-compile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <!-- Replacing default-testCompile as it is treated specially by Maven -->
+                    <execution>
+                        <id>default-testCompile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <execution>
+                        <id>java-compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>java-test-compile</id>
+                        <phase>test-compile</phase>
+                        <goals>
+                            <goal>testCompile</goal>
+                        </goals>
+                    </execution>
+                </executions>
             </plugin>
             <plugin>
                 <artifactId>maven-surefire-plugin</artifactId>

extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/Callback.java

@@ -16,7 +16,10 @@
 
 import io.quarkus.arc.deployment.TransformedAnnotationsBuildItem;
 import io.quarkus.arc.processor.Annotations;
+import io.quarkus.arc.processor.BeanInfo;
 import io.quarkus.arc.processor.DotNames;
+import io.quarkus.arc.processor.KotlinDotNames;
+import io.quarkus.arc.processor.KotlinUtils;
 import io.quarkus.gizmo.BytecodeCreator;
 import io.quarkus.gizmo.FieldDescriptor;
 import io.quarkus.gizmo.ResultHandle;
@@ -35,15 +38,17 @@ public class Callback {
     public final Target target;
     public final String endpointPath;
     public final AnnotationInstance annotation;
+    public final BeanInfo bean;
     public final MethodInfo method;
     public final ExecutionModel executionModel;
     public final MessageType messageType;
     public final List<CallbackArgument> arguments;
 
-    public Callback(Target target, AnnotationInstance annotation, MethodInfo method, ExecutionModel executionModel,
-            CallbackArgumentsBuildItem callbackArguments, TransformedAnnotationsBuildItem transformedAnnotations,
-            String endpointPath, IndexView index) {
+    public Callback(Target target, AnnotationInstance annotation, BeanInfo bean, MethodInfo method,
+            ExecutionModel executionModel, CallbackArgumentsBuildItem callbackArguments,
+            TransformedAnnotationsBuildItem transformedAnnotations, String endpointPath, IndexView index) {
         this.target = target;
+        this.bean = bean;
         this.method = method;
         this.annotation = annotation;
         this.executionModel = executionModel;
@@ -104,6 +109,15 @@ public boolean isReturnTypeMulti() {
         return WebSocketDotNames.MULTI.equals(returnType().name());
     }
 
+    public boolean isKotlinSuspendFunction() {
+        return KotlinUtils.isKotlinSuspendMethod(method);
+    }
+
+    public boolean isKotlinSuspendFunctionReturningUnit() {
+        return KotlinUtils.isKotlinSuspendMethod(method)
+                && KotlinUtils.getKotlinSuspendMethodResult(method).name().equals(KotlinDotNames.UNIT);
+    }
+
     public boolean acceptsMessage() {
         return messageType != MessageType.NONE;
     }

extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/KotlinContinuationCallbackArgument.java

@@ -0,0 +1,17 @@
+package io.quarkus.websockets.next.deployment;
+
+import io.quarkus.arc.processor.KotlinUtils;
+import io.quarkus.gizmo.ResultHandle;
+
+public class KotlinContinuationCallbackArgument implements CallbackArgument {
+    @Override
+    public boolean matches(ParameterContext context) {
+        return KotlinUtils.isKotlinContinuationParameter(context.parameter());
+    }
+
+    @Override
+    public ResultHandle get(InvocationBytecodeContext context) {
+        // the actual value is provided by the invoker
+        return context.bytecode().loadNull();
+    }
+}